Operating Regimes of Internal Combustion Engines in Hybrid Renewable Energy Systems for Power and Fuel Co-Generation

Solar–Wind–Biomass hybrid renewable energy systems (SWB-HRES) are important because they combine multiple energy sources to provide a more reliable and sustainable power supply. Since solar and wind energy are weather-dependent, integrating biomass helps ensure continuous electricity generation when sunlight or wind is limited. These hybrid systems reduce dependence on fossil fuels, lower greenhouse gas emissions, and support energy security. This research presents a comprehensive investigation of the operational strategies of internal combustion engines (ICEs) in SWB-HRES, designed for power and fuel co-generation. The study employs a methodological framework that uses HOMER Pro to simulate and optimize system configurations tailored to specific geographic and technical constraints. The core methodology focuses on identifying and modeling four distinct operational regimes for ICEs, which serve as versatile energy-storage and stabilization components. The proposed configurations include: (1) a standalone SWB-HRES without battery storage, where the ICE operates in a load-matching mode; (2) a battery-integrated standalone system where the battery’s state-of-charge thresholds dictate engine cycles; (3) an off-grid configuration coupled with hydrogen production via water electrolysis, where the ICE responds to renewable energy deficits; and (4) a grid-connected SWB-HRES scenario with pre-defined operating schedules for both electricity export and fuel synthesis. The analysis meticulously details the technical parameters for each scenario, including component sizing, energy flow management, and the integration of flexible fuel supply systems capable of handling syngas, biogas, and hydrogen blends.